The Diesel Garage banner

1 - 15 of 15 Posts

·
Junior Member
Joined
·
132 Posts
Discussion Starter #1
How many of you guys have needed 3406 exhaust manifold studs drilled out/replaced? Did your exhaust leak at the manifold?
 

·
Junior Member
Joined
·
316 Posts
3406 exhaust studs break all the time.
 

·
Junior Member
Joined
·
3,533 Posts
If you expect to work on any of the cats you will become a expert at drilling straight threw the exhaust studs, It is easy with a standard drill, and bit, when you have to use an angle drill and shortened bits that is when you really separate, the prows. Learning how to sharpen a drill bit properly for different metals.
Removing one that is shattered a half inch inside the head gets interesting.
I have a set of alignment dowels that really cut back on the amount of studs that break.
 

·
O'Skool Member
Joined
·
579 Posts
3406 exhaust studs break all the time.
PITA! :gaah

Had the short one under the turbo break. In the process of removing the log 5 more broke - 1 on each hole.

Bought some Harris Missile-Weld rods. Do a 1 second zap then peen, repeat slowly, not getting stud too hot.. Takes forever. :popcorn Then when you have built it out enough weld a nut on and turn out stud and shout and do cart wheels!:woohoo

Not having an auto-darkening helmet didn't help matters either.:thumbdown

I had 1 on No.5 I that just kept breaking so I welded an old stud to it and only torqued the nut to 10 ftlb and so far no gasket leak.

Good luck on yours.
 

·
Junior Member
Joined
·
237 Posts
If you expect to work on any of the cats you will become a expert at drilling straight threw the exhaust studs, It is easy with a standard drill, and bit, when you have to use an angle drill and shortened bits that is when you really separate, the prows. Learning how to sharpen a drill bit properly for different metals.
Removing one that is shattered a half inch inside the head gets interesting.
I have a set of alignment dowels that really cut back on the amount of studs that break.
John can you elaberate a little on the dowels. Thanks
 

·
Junior Member
Joined
·
3,533 Posts
The dowels are about 7/8 machined tube with a machined step in them that you put in the round holes in the manifold to keep the manifold centered and that way the studs do not rest on the studs. The older manifolds you had to drill them out. If I had them hear I would measure them, from memory they are about 4 inches long drilled out to 3/8 and have 11/16 step. Measure the hole in most manifolds for the correct size. One is round, other is elliptical. Three studs never-size the slip joints, and they are good to go.
Put the manifold on with the dowels and then all the spacers and nuts, snug, tap the dowels and tighten the bolts a little more and put on other pieces. Torque to I still do 35LBS with lots of never-size, ATF, gear oil, mixed to a thin paste.
 
  • Like
Reactions: cowpuncher

·
Junior Member
Joined
·
316 Posts
copper anti size works wonder when you are doing install. use liberal amounts!
 

·
Tribal
Joined
·
167 Posts
A good wash prior to inspection will certainly help mask the blowbye, maybe packing the gap (if any) with JB-Weld would ease your mind when they are walking around. My shop I don't think did more than a visual walk around, then again I don't cross many scales anymore..
Without question, 3406's A&B have weakness on exhaust manifold studs, for such a great Engine one would think that would of been improved over the years. I have had a 425b and now a 400a, both have had studs replaced, more than once. I even carry a few spare in my toolbox. Anti-seize (haven't tried the copper) helps, DO NOT OVER TORQUE them. One answer hear mentions something about centering sleeves? I have the offsets but they don't center anything. Wonder if both my Cats were re-dun and not replaced?
I am missing one now that I couldn't get out since I missed the center when attempting to drill for an easy-out, apparently it's a knack a driver O/O will have to learn and a mechanic can do eyes shut!
 

·
Junior Member
Joined
·
3,533 Posts
Drilling threw a stud is an acquired thing, I have drilled out thousands and with rapidity you learn a few things. If you drill it off center and can not get it out then drill oversize and force it over to center then put in a helicoil.
 
  • Like
Reactions: tribaltrans

·
Junior Member
Joined
·
1,811 Posts
How many of you guys have needed 3406 exhaust manifold studs drilled out/replaced? Did your exhaust leak at the manifold?
First off, leave drilling as a LAST resort. Take a wire brush on a drill and clean all around the stud. Take some 3/8 flat washers and start welding (mig welder) them to the stud. Even if it is countersunk in the hole, let the wire hit the stud and work its way out to the washer. Let it cool a few moments, then weld another to it, then another. Lightly tap the top, with a hammer pushing in on the stud. Use channel locks and start twisting either way.

The theory is to make the stud hot and then cool, with every washer. Expand and contract, until it works loose. Drilling is shooting in the dark. one wrong move, and the head is FUBAR. Too deep and you hit water.

Next drill out the slotted holes in the manifold to 1/2 inch. Then when you mount the manifold, center all the studs in the holes. Stagger torque to 42 lbs, and good to go. You may have to expand or contract the manifold to line up the holes.

Not trying to influence anyone, but I stopped drilling years ago. I have yet to have a stud not come out, by welding a washer to it. By the time you break bits, easy outs, and cuss and cry....you can weld a washer to it, and back it out.
 

·
Junior Member
Joined
·
3,533 Posts
Personally I have a lot of fear when it comes to welding on an engine. Especially the cylinder head. ECMs are just not that cheap. When the head is off no problem, weld away. Just a thought!
 

·
Junior Member
Joined
·
119 Posts
i've had good luck with a set of left handed drill bits. more often than not the bit turns the broken stud right out before drilling very deep.:hump
 

·
Junior Member
Joined
·
316 Posts
i have welded nuts and bolt to the studs.
 
1 - 15 of 15 Posts
Top